As the teaching union conference season begins, teachers have issued a stark warning to the Government: reduce our workload or we'll go on strike.

Wales's four biggest unions are to discuss identical motions calling for industrial action if demands for a limit to the working week are not met.

The demand has been made in the unions' submissions to the School Teachers Review Body (STRB), the body which advises ministers on pay and conditions.

If they are not satisfied with the response, strike action could follow, which would see teachers on a four-day week.

The threat points to a hardening of opinion among the teaching unions, who made similar demands a year ago and say there has been little progress since then.

Geraint Davies, secretary of the National Association of Schoolmasters and Union of Women Teachers Cymru, said, "It has to come to a head as far as I'm concerned. Enough is enough.

"If you speak to any teacher they will tell you workload is at the fore-front of the agenda.

"We've done a survey among our members which shows at least half the teachers surveyed work in excess of 50 hours a week.

"Come the conference we will see an entrenchment of opinion. As things stand, industrial action is a possibility."

Gethin Lewis, secretary of the National Union of Teachers Cymru, said he was concerned education appeared to be slipping down the Westminster Government's agenda.

He said, "If we don't get proper resources, then teachers in the main unions will consider strike action."

The threat of strike action should be taken seriously, Mr Lewis added.

He said, "The unions are discussing the same motion as a warning to the Government that we are speaking with a united voice."

The Comprehensive Spending Re-view, due in July, could also provide a trigger for strike action.

"Both the Government and the National Assembly need to watch this

carefully," Mr Lewis said.

"If there are not adequate resources for teaching, nobody will want to be a teacher or a head teacher any longer."

Proposals to widen the role of classroom assistants are also proving controversial, criticised as a cheap solution to staffing problems.

Mr Lewis said, "There is a role for

classroom assistants but their role should be complementary. We should have additional classroom assistants who are properly qualified."

Today sees the start of the Association of Teachers and Lecturers' (ATL) annual conference, to be held in St David's Hall, Cardiff.

Vaughan Richards of the ATL said, "The workload issue is crucial because teachers now hardly have time to breathe.

"The issue has got to be resolved, that's the bottom line. If it isn't, then we will ballot members."

The ATL's involvement in the ballot threat is all the more significant as it is usually seen as the most moderate teaching union. Edwyn Williams, General secretary of Welsh teachers' union Ucac, said, "We are pressing the STRB to look at our demands for maximum hours and a time set aside for other tasks."